so i am thinking about buying a 80cc motorized bike kit to put onto my mountain bike. the topspeed is 3 40mph or approx 65kmh i have some concerns about the safety of such a device... 65kmh is pretty damn fast and i am worried how well my mountain bike will hold up at these speeds when it is only made to withstand speeds attained by leg power. also, how about the brakes i already have on my bike? will they really withstand these speeds? will i hqave to buy special ones? also, should i only be driving my motorbicycle on the Road? or should i be on the sidewalk?